1. Field of the Invention
The present invention generally relates to the field of wireless communication and more particularly relates to a method and system for optimizing user equipment performance in long term evolution Frequency division duplexing (FDD) and Time division duplexing (TDD) co-existent networks.
2. Description of the Related Art
With the increase in the number of wireless technology subscribers, there is a dearth in the available resources that can be allocated to a subscriber. This has led to the introduction of a lot of new techniques as well and methods for allocating more users or providing more resources to each subscriber, including the use of increased bandwidth or additional bands. Apart from these, many operators around the globe are preparing for joint deployment of time division multiplexing (TDD) and frequency division multiplexing (FDD) based systems where TDD based systems can provide the freedom to configure variable number of resources for downlink and uplink. Interworking between LTE FDD and LTE TDD in networks will be of increasing importance for operators that have spectrum for both LTE modes. It will allow operators to seamlessly offer Mobile Broadband services on FDD and TDD spectrum, increasing capacity and improving consumer experience. Many operators with FDD-LTE networks also own spectrum suitable for TDD-LTE services. With offloading capability, the two LTE modes can work hand in glove as shown in FIG. 1. As multimode devices supporting both FDD and TDD-LTE become more common, operators will be able to take full advantage of their spectrum allocations and deploy TDD-LTE as an integral part of their overall mobile broadband service. There are various ways in which handover can be triggered from FDD to TDD or vice versa. The network triggers the handover procedure e.g. based on radio conditions, load. Few conventional mechanisms are                RRC Connection Release with Redirection between TDD and FDD        TDD to FDD and FDD to TDD Inter-Frequency handover (X2 & S1) with traffic. This includes:                    a) Different triggers-based handover i.e. with measurement reports            b) Blind FDD/TDD handover, i.e. without having received measurement reports            c) The possible UE scenario where handover can be triggered                        Case 1: NW may move the UE to TDD/FDD during establishment of VOLTE calls or during VOLTE call itself        Case 2: NW may initiate the connected mode handover during the Attach/TAU/NAS procedure        Case 3: NW may initiate the handover during data call due to load balancing or poor radio condition        
Assuming a case where EUTRAN TDD-FDD joint deployment is present at the same place, the following deployments are possible:
1. Multiple FDD cells and 1 TDD cell.
2. Multiple TDD cells and 1 FDD cell.
3. 1 FDD cell and 1 TDD cell overlapped with same or different coverage.
4. 1 TDD cell with 1 neighbor FDD cell and vice versa
5. FDD cells alone
6. TDD cells alone
The current standards do not address to handle error cases possible during mobility between TDD-FDD and vice-versa.
Therefore, there is need for method and system for optimizing user equipment performance in long term evolution FDD and TDD co-existent networks in order to provide faster resumption of service while moving from TDD to FDD area or vice versa.